George,

Very nice. I have to say though that this offers up the same problem I had when I used the common "2 String" crossed diffraction mask. As very small movements in focus can be seen it is still a judgement call as to when both spikes are symmetrical. When I switched to the Bahtinov my images were substantially improved as I found it much easier to decipher the split of perfect focus. I have tried the B. Mask by eye and than run several V curves with FocusMax and found it to be redicuously accurate. I will give your mask a try though.